1. Field of the Invention
The present invention relates to an external power source for an electronic flash unit for use in a camera.
2. Related Background Art
As the external power source for an electronic flash unit for use in a camera, there have been used various types such as a high-voltage piled battery, or a DC-DC converter for obtaining a high voltage from a small low-voltage battery.
However, the piled battery conventionally used as the external power source for the electronic flash unit is poor in portability because of its bulkiness and large weight, and is expensive, giving economic burden to the user.
On the other hand, the power source utilizing voltage elevation by the DC-DC converter from a small low-voltage battery is free from the above-mentioned drawbacks of the piled battery, but is associated with wasted current because of the continued voltage elevating operation of the DC-DC converter, so that the life of the battery is shortened if the power supply is turned on for a long time.